Mr Gandhi is not standing in the election, but he has been the face, and the focus, of the ailing Congress Party's campaign.

A good result for Congress (though the party is not expected to win) will be seen as proof of Mr Gandhi's leadership credentials and burnish his claims to the prime ministership.

Advertisement

Mr Modi styles himself as the self-made man who has single-handedly delivered Gujarat its impressive development: he has brought uninterrupted electricity, sealed roads and street lights to the state.

But while he has won praise for the economy, Mr Modi has been criticised for his intolerance of political opposition.

He was chief minister during the infamous Gujarat riots in 2002. A train carrying Hindu pilgrims was burnt by a Muslim mob in Godhra, sparking anti-Muslim riots that raged for months across the state.

More than 1000 people were killed and his government was accused of being complicit in attacks on Muslims and actively fomenting the violence of Hindu vigilantes.

He remains a deeply divisive figure across the country and internationally.

After years of bans, only this year have Britain and the US said they would allow Mr Modi to apply for a visa.

He is expected to win the election handsomely, with some forecasting 130 seats out of a possible 182 for his party. But he will need a showing at least that strong to establish his national bona fides.

Mr Gandhi, perhaps unwisely given his own privileged background, has (without naming him) attacked Mr Modi as out of touch and accused him of taking credit for the industry of the Gujarati people.

''Here you toil hard and sweat it out … but it is only one man who takes the credit in Gujarat,'' he told a Congress rally.

''Do you have electricity? Do you have water? Do the youths here have jobs? The voice of the common man, poor, youth, and women should be heard. You bring about development in the state, not a single person.''

Mr Modi has not been nearly so reticent, addressing Mr Gandhi as baba, a child needing nurturing.

''Today, Rahul baba is here in Palanpur,'' he told a huge rally in the northern city. ''Rahul baba, when you are on the helicopter, do you see the large crowd? Rahul Gandhi, my father was not the PM. He was not even a sarpanch [village chief]. Still people love me.''